Worlds have generic plane, and box colliders for physics collisions already. You could probably reliably convert them to Phys Bone box/plane colliders to make peoples Phys bones collide with the wall and floor. You would have normal unity colliders and Phys bone colliders on the same object letting you stand on it and have your bones hit it. I would also suggest a toggle in the Phys bone script to have world collision or off.